determine_image_resolution
For each image, fetch the width and height in pixels from images [] and the width and height in point from the TET_image_info structure. Determine the image resolution in dpi. As the meaning of the dpi information changes if the image is rotated or skewed, a warning is printed in these cases.
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import java.io.PrintStream;
import java.io.UnsupportedEncodingException;
import java.text.NumberFormat;
import com.pdflib.TET;
import com.pdflib.TETException;
/**
* For each image, fetch the width and height in pixels from images[] and the
* width and height in point from the TET_image_info structure. Determine the
* image resolution in dpi. As the meaning of the dpi information changes
* if the image is rotated or skewed, a warning is printed in these cases.
* <p>
* Required software: TET 3
* <p>
* Required data: PDF document
*
* @version $Id: determine_image_resolution.java,v 1.3 2008/11/21 09:46:55 stm Exp $
*/
public class determine_image_resolution
{
/**
* Global option list
*/
static final String GLOBAL_OPTLIST = "searchpath={../resource/cmap "
+ "../resource/glyphlist ../input}";
/**
* Document-specific option list
*/
static final String DOC_OPTLIST = "";
/**
* Page-specific option list
*/
static final String PAGE_OPTLIST = "granularity=page";
/**
* Basic image extract options (more below)
*/
static final String BASE_IMAGE_OPTLIST = "compression=auto format=auto";
/**
* The encoding in which the output is sent to System.out. For running the
* example in a Windows command window, you can set this for example to
* "windows-1252" for getting Latin-1 output.
*/
private static final String OUTPUT_ENCODING = System
.getProperty("file.encoding");
/**
* For printing to System.out in the encoding specified via OUTPUT_ENCODING.
*/
private static PrintStream out;
public static void main(String argv[]) throws UnsupportedEncodingException {
System.out.println("Using output encoding \"" + OUTPUT_ENCODING + "\"");
out = new PrintStream(System.out, true, OUTPUT_ENCODING);
TET tet = null;
try {
if (argv.length != 1) {
throw new Exception(
"usage: determine_image_resolution <filename>");
}
NumberFormat dpiFormat = NumberFormat.getInstance();
dpiFormat.setMinimumFractionDigits(0);
dpiFormat.setMaximumFractionDigits(2);
tet = new TET();
tet.set_option(GLOBAL_OPTLIST);
int doc = tet.open_document(argv[0], DOC_OPTLIST);
if (doc == -1) {
throw new Exception("Error " + tet.get_errnum() + "in "
+ tet.get_apiname() + "(): " + tet.get_errmsg());
}
/* get number of pages in the document */
int n_pages = (int) tet.pcos_get_number(doc, "length:pages");
/* loop over pages */
for (int pageno = 1; pageno <= n_pages; ++pageno) {
int page = tet.open_page(doc, pageno, PAGE_OPTLIST);
if (page < 0) {
print_tet_error(tet, pageno);
continue; /* try next page */
}
/* Retrieve all images on the page */
int imageno = 0;
while (tet.get_image_info(page) == 1) {
/*
* Calculate the DPI values for x and y direction, and
* warn if the image is rotated or skewed.
*/
String imagePath = "images[" + tet.imageid + "]";
int width = (int) tet.pcos_get_number(doc,
imagePath + "/Width");
int height = (int) tet.pcos_get_number(doc,
imagePath + "/Height");
double xDpi = 72 * width / tet.width;
double yDpi = 72 * height / tet.height;
out.println("Page " + pageno + " image " + imageno + ": "
+ "resolution (DPI): x="
+ dpiFormat.format(xDpi) + " y="
+ dpiFormat.format(yDpi));
if (tet.alpha != 0 || tet.beta != 0) {
out.println(
" Warning: image is rotated and/or skewed (alpha="
+ tet.alpha + ", beta=" + tet.beta + "), "
+ "DPI value may be meaningless");
}
imageno++;
}
if (tet.get_errnum() != 0) {
print_tet_error(tet, pageno);
}
tet.close_page(page);
}
tet.close_document(doc);
}
catch (TETException e) {
System.err.println("TET exception occurred in extractor sample:");
System.err.println("[" + e.get_errnum() + "] " + e.get_apiname()
+ ": " + e.get_errmsg());
}
catch (Exception e) {
System.err.println(e.getMessage());
}
finally {
if (tet != null) {
tet.delete();
}
}
}
/**
* Report a TET error.
*
* @param tet
* The TET object
* @param pageno
* The page number on which the error occurred
*/
private static void print_tet_error(TET tet, int pageno) {
System.err.println("Error " + tet.get_errnum() + " in "
+ tet.get_apiname() + "() on page " + pageno + ": "
+ tet.get_errmsg());
}
}